But there is one kind of spending Americans by and large will not do. They will not spend dollar coins. Americans are unfazed by the fact that we are the only country whose most common currency is not a coin. We are not envious of the euro coin, not even the 2-euro coin.

The coin has all kinds of advantages, the two biggest being that it lasts longer than the paper bill and it offers expanded opportunities for vending machines and transit authorities.

The public just doesn't care. People who get a dollar coin in their change generally drop it in a jar and leave it there. In the curious way money works, this is in effect extending the government an interest-free loan equivalent to that stash of coins. If you want to make the Treasury sweat, even more than it is already, take the coins and buy a T-bill, just like the Chinese.

Undaunted by this overwhelming lack of interest in dollar coins, the government has tried three times to entice its normally free-spending citizenry to spend dollar coins.

From 1979 to 1981 it minted 41 million Susan B. Anthony coins. Anthony was a tireless advocate of suffrage, abolition, equal rights for women and temperance; well, three out of four isn't bad.

Despite the catchy name, the Susie, it failed to catch on and most of those coins are still around somewhere, just not in general circulation. The last of the Susies was minted in 1999 as boxed proof sets in hopes collectors would snap them up. It took five years to unload them all.

In 2000 the government came out with what seemed the most promising coin yet, the Sacagawea, the tough, very able and smart Shoshone woman who accompanied the Lewis and Clark expedition. The coin features a fetching image of Sacagawea, with her baby, Jean Baptiste, peeping over her shoulder.

You'd have to be pretty cold-hearted not to want to carry around a pocket full of Sacagaweas, but that coin too went unspent although it is still being minted.

In 2005, Congress passed the Presidential Coin Act, calling for a coin to honor all the presidents to be minted at a rate of four presidents a year. This year we're up to Andrew Johnson, Ulysses Grant, Rutherford Hayes and James Garfield. Only 24 presidents to go.

This program isn't doing well either, but Congress isn't going to pull the plug on it. What parent wants to face a sobbing young numismatist, "But, daddy, where's my Chester A. Arthur and Grover Cleveland? Congress promised, and Congress would never break a promise, would it?"

The upshot of this, according to the earnest sleuths at NPR's Planet Money, is that 1 billion dollar coins are just sitting in a Baltimore warehouse waiting for some consumer to adopt them.

Sixty percent of the coins are in circulation, NPR says, but you couldn't prove this by most people because they never see them. The other 40 percent are just sitting there. It is said that the Fed is running out of space for them.

The government could play hardball by insisting that all tax refunds be redeemed in dollar coins, but it won't. In the meantime, there's always Yucca Mountain.